1. Field of the Invention
The present invention relates to a new type of phosphorus containing epoxy resin compositions with flame retardant and a resin sheet.resin clad metal foil.prepreg.laminated board.multi layer board used for an electric circuit board containing said epoxy resin.
2. Description of the Prior Art
To copper clad laminates, which are in use for electronic or electric apparatus and devices, the measures such as fire prevention or retardation are strongly required. Therefore, halogenated epoxy resins that have flame retardance are usually in use for copper clad laminates. Especially, among halogen group of atoms, by introducing bromine into epoxy resin, an excellent flame resistance can be provided to the epoxy resin and its cured product that has highly reactive epoxy groups and characteristics can be obtained, therefore, the halogenated epoxy resins, especially brominated epoxy resins are known to useful material for electronic or electric devices. However, when these halogenated epoxy resin are used at high temperatures for a long term, they can be dissociated to form halogen compounds such as hydrogen halogenide and halogen, and subsequently might be a danger to occurring corrosion problem for wires, and such actual accidents have been already reported. Furthermore, it is pointed out that toxic chemical substances such as dioxin and hydrogen halogenide could be formed to incur a serious environmental problem. When used parts of electric and (or) electronic devices will be calcined. This indicates that use of halogen containing flame retardant could result in such environmental problem. Considering the present situation of epoxy resin composition, the research to develop a new epoxy resin compositions substitute for halogenated epoxy resins is highly required. Under the current situation, the development and commercialization of a flame retardant epoxy resin not containing any halogen and a copper clad laminated for printed wiring applications using that said flame retardant epoxy resin can be said as a subject to meet the current requirement of the era.